Valve prosthesis

ABSTRACT

Heart valve prostheses are provided having a self-expanding frame that supports a valve body comprising a plurality of coapting leaflets. The valve body may include a first leaflet, a second leaflet, and a third leaflet, wherein the second leaflet extends between the first leaflet and the third leaflet such that the first and third leaflets are separated from each other by the second leaflet. The leaflets are constructed with four commissure points to reduce the stress and strain applied to the commissure points and to efficiently distribute forces along the leaflets and to the frame. As such, the first and second leaflets may be sewn together to form a first commissure point and a second commissure point, and the second and third leaflets may be sewn together to form a third commissure point and a fourth commissure point, with the four commissure points being sewn to the frame.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to artificial heart valves. Morespecifically, the present invention is directed to artificial valveprosthesis.

2. Background Art

Cardiac valves exhibit two types of pathologies: regurgitation andstenosis. Regurgitation is the more common of the two defects.Typically, either defect is treated by a surgical repair. Under certainconditions, however, the cardiac valve must be replaced. Standardapproaches to valve replacement require cutting open the patient's chestand heart to access the native valve. Such procedures are traumatic tothe patient, require a long recovery time, and can result in lifethreatening complications. Therefore, many patients requiring cardiacvalve replacement are deemed to pose too high a risk for open heartsurgery due to age, health, or a variety of other factors. These patientrisks associated with heart valve replacement are lessened by theemerging techniques for minimally invasive valve repair, but still manyof those techniques require arresting the heart and passing the bloodthrough a heart-lung machine.

Efforts have been focused on percutaneous transluminal delivery ofreplacement cardiac valves to solve the problems presented bytraditional open heart surgery and minimally-invasive surgical methods.In such methods, a valve prosthesis is compacted for delivery in acatheter and then advanced, for example, through an opening in thefemoral artery and through the descending aorta to the heart, where theprosthesis is then deployed in the aortic valve annulus.

In view of the foregoing, it would be desirable to provide a valveprosthesis that is capable of conforming to a patient's anatomy whileproviding a uniform degree of rigidity and protection for critical valvecomponents. Protection for critical valve components is essential tomaintain reliability for the valve prosthesis.

BRIEF SUMMARY OF THE INVENTION

Provided herein are valve prostheses that generally include aself-expanding frame, where the valve prostheses are sutured to theself-expanding frame. Such configurations achieve numerous goals. Forexample, such configurations can: prevent the native leaflets fromobstructing flow through the left ventricular outflow tract (LVOT);prevent the native leaflets from interacting with the prostheticleaflets; recruit the native leaflets in minimizing perivalvular leaks;maintain proper alignment of the valve prosthesis; avoid systolicanterior mobility; and maintain valve stability by preventing migrationof the valve into the atrium or ventricle. The design of the prosthesisalso mimics the native valve and supports a non-round in vivoconfiguration, which better reproduces native valve function.

In view thereof, disclosed herein are aspects of a valve prosthesiswhich is generally designed to include a valve body and a self expandingframe. The valve body includes a first leaflet, a second leaflet, and athird leaflet. Adjoining leaflets are sewn together to form a firstcommissure point, a second commissure point, a third commissure point,and a fourth commissure point. The four commissure points are sewn tothe frame.

In another exemplary embodiment, the valve prosthesis is designed toinclude a valve body including a first leaflet, a second leaflet, athird leaflet, and a fourth leaflet, and a self expanding frame. Thefirst leaflet is attached to the second leaflet at a first point to forma first commissure point. The second leaflet is attached to the thirdleaflet at a second point to form a second commissure point. The thirdleaflet is attached to the fourth leaflet at a third point to form athird commissure point. The commissure points are sewn to the frame.

Disclosed herein are aspects of a method of treating a valve disorder ina patient's heart including loading a valve prosthesis onto a deliverysystem, advancing the delivery system and valve prosthesis through anincision into the patient's vasculature and into the patient's heart,releasing the valve prosthesis from the delivery system, and withdrawingthe delivery system from the patient's heart. The valve prosthesisincludes a valve body and a self-expanding frame. The valve bodyincludes a first leaflet, a second leaflet, and a third leaflet.Adjoining leaflets are sewn together to form a first commissure point, asecond commissure point, a third commissure point, and a fourthcommissure point. The four commissure points are sewn to the frame.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying figures, which are incorporated herein, form part ofthe specification and illustrate embodiments of a valve prosthesis.Together with the description, the figures further serve to explain theprinciples of and to enable a person skilled in the relevant art(s) tomake, use, and implant the valve prosthesis described herein. In thedrawings, like reference numbers indicate identical or functionallysimilar elements.

FIG. 1 is a perspective view of a valve prosthesis, in accordance withan aspect of the disclosure.

FIG. 2 is a side view of a valve prosthesis.

FIG. 3 is a top view of a valve prosthesis.

FIG. 4 is a top view of a valve prosthesis according to an alternateaspect of this disclosure.

FIG. 5 is a top view of a valve prosthesis according to an alternateaspect of this disclosure.

FIG. 6 is a top view of a valve prosthesis according to an alternateaspect of this disclosure.

FIG. 7 is a top view of a valve prosthesis according to an alternateaspect of this disclosure.

FIG. 8 is a top view of a valve prosthesis according to an alternateaspect of this disclosure.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description of a valve prosthesis refers to theaccompanying figures that illustrate exemplary embodiments. Otherembodiments are possible. Modifications can be made to the embodimentsdescribed herein without departing from the spirit and scope of thepresent invention. Therefore, the following detailed description is notmeant to be limiting.

The present invention is directed to a heart valve prosthesis having aself-expanding frame that supports a valve body. The valve prosthesiscan be delivered percutaneously to the heart to replace the function ofa native valve. For example, the valve prosthesis can replace a bicuspidor a tricuspid valve such as the aortic, mitral, pulmonary, or tricuspidheart valve.

In one aspect of the invention, the valve body comprises three leafletsthat are fastened together at enlarged lateral end regions to formcommissural joints, with the unattached edges forming the coaptationedges of the valve. The leaflets can be fastened to a skirt, which inturn can be attached to the frame. The upper ends of the commissurepoints define an outflow or proximal portion of the valve prosthesis.The opposite end of the valve at the skirt defines an inflow or distalportion of the valve prosthesis. The enlarged lateral end regions of theleaflets permit the material to be folded over to enhance durability ofthe valve and reduce stress concentration points that could lead tofatigue or tearing of the leaflets. The commissural joints are attachedabove the plane of the coaptation edges of the valve body to minimizethe contacted delivery profile of the valve prosthesis.

Referring to FIGS. 1 and 2, from a top view, valve prosthesis 1 includesa circular frame 11. Frame 11 can be any non-biological structureincluding wireforms, stents, and the like. In alternate aspects of theinvention, frame 11 can be elliptical, D-shaped, or any other shapeknown to a person of ordinary skill in the art. From a side view, frame11 can be tapered, cylindrical, conical, or any other shape known to aperson of ordinary skill. Frame 11 can be a self-expanding structureformed by laser cutting or etching a metal alloy tube comprising, forexample a shape memory material such as nickel titanium (nitinol).Alternatively, frame 11 can be a balloon expanding structure. Frame 11can include a pattern of radial cells that make up the structure offrame 11. The cell sizes can be modified during the formation of frame11, for example through an expansion step. In addition, the number ofcells in a radial or axial direction can be modified to allow for alarger or fewer number of cells. Frame 11 can also include a cusp 91.Cusp 91 can be a radiopaque imaging reference to assist in positioningthe valve prosthesis 1 in a native valve annulus. Cusp 91 can alsoassist in anchoring frame 11 in the native valve annulus.

Valve prosthesis 1 also includes a valve 21 that includes individualleaflets that are assembled to the skirt. The leaflets and skirt areformed from a natural or man-made material. Preferred materials forvalve 21 include mammalian tissue, such as porcine, equine, or bovinepericardium, or a synthetic or polymeric material. In one aspect of theinvention, valve 21 includes three leaflets 31 a-c. Adjoining pairs ofleaflets are attached to one another to form commissure points 41 a-d.Leaflet 31 b is attached to leaflet 31 a by commissure points 41 a and41 d. Leaflet 31 b is attached to leaflet 31 c by commissure points 41 band 41 c. In a preferred embodiment, valve prosthesis 1 is biased to aclosed position. Alternatively, valve prosthesis 1 can be biased to anopen position. Free edges of leaflets 31 b and 31 a come together toform coaptation edge 51 a, thereby creating a competent seal. Free edgesof leaflets 31 b and 31 c come together to form coaptation edge 51 b,thereby creating a competent seal. The length of coaptation edges 51 aand 51 b can be from approximately 24 mm to approximately 48 mm. In apreferred embodiment, the length of coaptation edges 51 a and 51 b isapproximately 25 mm.

In one aspect of the invention, the contact area between the leaflets atcoaptation edges 51 a and 51 b is minimized to allow for quicker openingand closing of valve leaflets 31 a-c. For example, at coaptation edge 51a, approximately 0.5 mm to approximately 6 mm of valve leaflets 31 a and31 b touch along the length of coaptation edge 51 a. However, thecontact area of the leaflets at coaptation edges 51 a and 51 b isaffected by the positioning of valve prosthesis 1 in the native anatomy.In one aspect of the invention, after implantation, valve prosthesis 1takes approximately 0.06 seconds to open from a closed configuration.Valve prosthesis 1 takes approximately 0.04 seconds to close from anopen configuration. Valve prosthesis 1 is also able to operate atapproximately 167 ml/second of fluid.

The bases of leaflets 31 a-c are assembled to a skirt 71 and attached toframe 11. Commissure points 41 a-d are positioned on frame 11 such thatleaflet 31 b extends across the center of frame 11, as shown in FIG. 3.Valve prosthesis 1 can include center member 81. In one aspect of theinvention, center member 81 attaches to frame 11 between commissurepoints 41 a and 41 b and between commissure points 41 c and 41 d. Centermember 81 can be semi-rigid or rigid and can be a suture, nitinol wire,or a synthetic or polymeric material that will not generate a thromboticresponse in a patient, or any other material known to a person ofordinary skill in the art. In one aspect of the invention, center member81 is attached to frame 11 on the outflow side of leaflet 31 b.Alternatively, center member 81 can be attached to frame 11 on theinflow side of leaflet 31 b. Center member 81 restricts the movement ofleaflet 31 b and prevents leaflet 31 b from collecting blood andparachuting in the outflow direction in the presence of blood flow. As aresult, during blood flow, the free edges of leaflet 31 b fold alongcenter member 81 and minimize the area of leaflet 31 b extending acrossthe orifice area of valve prosthesis 1.

In another aspect of the invention, each commissure point is attached toframe 11 by sewing the commissure point to a cell of frame 11 such thateach commissure point occupies an entire cell of frame 11.Alternatively, each commissure point can be attached to frame 11 bysewing the commissure point to a portion of a cell of frame 11. In apreferred embodiment, at least one cell of frame 11 is positionedbetween commissure points 41 a and 41 b and commissure points 41 c and41 d. Further, at least two cells can be positioned between commissurepoints 41 b and 41 c and commissure points 41 a and 41 d. In one aspectof the invention, commissure points 41 a-d are disposed longitudinallyoffset from coaptation edges 51 a-b of the valve body, therebypermitting a smaller delivery profile. Due to the presence of leaflet 31b across the center of frame 11, valve prosthesis 1 may require adelivery system that features an asymmetric member so that the deliverysystem doesn't interfere with leaflet 31 b. Alternatively, a deliverysystem for valve prosthesis 1 can grasp the outer edge of frame 11 todeliver valve prosthesis 1 into a native valve annulus.

The axial distance from the distal most portion of the base of the valveleaflets to the proximal most portion of the valve leaflets is theleaflet height, h2. The base of the valve leaflets is where the leafletedges attach to the skirt and the valve frame. In a preferredembodiment, h2 is from approximately 8 mm to approximately 15 mm. Theaxial distance between the distal and proximal portions of thecommissure points is the commissure height, h1. In a preferredembodiment, h1 is approximately 9 mm.

FIG. 3 shows valve 21 in the closed state. Commissure points 41 a-dattach to frame 11 and are positioned to form angles 61 a-d between therespective commissure points with the center of frame 11 as the vertexof the angles. Angles 61 a and 61 c can be larger than angles 61 b and61 d. In one aspect of the invention, angles 61 a and 61 c areapproximately 170 degrees. In an alternate embodiment, one or more ofangles 61 a-d can be modified to optimize the function of valveprosthesis 1 by positioning one or more commissure points 41 a-d at analternate portion or cell of frame 11 or by modifying the shape of oneor more of leaflets 31 a-c. For example, angles 61 a and 61 c can bebetween approximately 160 degrees and 180 degrees. Angles 61 a and 61 ccan also be between 90 degrees and 180 degrees. Modifying one or more ofangles 61 a-d can modify the length of coaptation edges 51 a and/or 51b. A longer coaptation edge length correlates to less stress oncommissure points 41 a-d.

In a further aspect of the invention, leaflets 31 a and 31 c areapproximately the same size. Alternatively, leaflets 31 a and 31 c canbe different sizes. Modifying the sizes of leaflets 31 a and 31 c canalso affect angles 61 a-d. For example, if leaflets 31 a and 31 c aredifferent sizes, angle 61 c can be larger than angle 61 a, or viceversa.

The configuration involving four commissure points can increase thecoaptation length of the valve leaflets. As a result, the fourcommissure points experience less deflection than a valve having threecommissure points. This allows the leaflets to maintain a rapid openingand closing time. The four commissure design also enables the valveprosthesis to maintain reliability with a low commissure height. The lowcommissure height allows valve prosthesis 1 to replace the native mitralvalve. Furthermore, a low commissure height correlates to a valveprosthesis that is shorter in the axial direction that is easier toposition and align in a native valve annulus. The four commissure pointsalso enable the valve to maintain hemodynamic performance in a severelyelliptical configuration by mitigating impact in the coaptive region.This configuration also provides a more uniform distribution of stressesalong coaptation edges 51 a-b of leaflets 31 a-c allowing valveprosthesis 1 to exhibit greater reliability and a longer operating lifethan current catheter delivered valve prostheses.

In an alternate aspect of the invention shown in FIG. 4, from a sideview, frame 13 is an hourglass shape where the outflow portion flaresout such that the diameter of the outflow portion of the frame is largerthan the diameter of the inflow portion of the frame. In one aspect ofthe invention, commissure points 43 a-d are angled outward from thecenter of frame 13. In this configuration, the most proximal portions ofcommissure points 43 a-d are further from the center of frame 13 thanthe distal portions of commissure points 43 a-d. In an alternateembodiment, the commissure points can be angled inward towards thecenter of the frame. The commissure points can also be orientedvertically on the frame, as shown in FIG. 3.

FIGS. 5-6 are top views of alternative aspects of the invention showingalternate frame shapes. In FIG. 5, from a top view, the frame is anelliptical shape. In this embodiment, leaflets 35 a and 35 c haveapproximately the same size and area and angles 65 a and 65 c areapproximately equal. In a preferred embodiment, angles 65 a and 65 c areapproximately 170 degrees. Furthermore, coaptation edges 55 a and 55 bare approximately equal in length. Similar to valve prosthesis 1discussed in FIGS. 1-3, the size and area of leaflets 35 a-c can bemodified so that leaflets 35 a and 35 c do not have approximately thesame size. The placement of commissure points 45 a-d on frame 15 canalso be modified to alter angles 65 a-d in order to optimize thefunction of valve prosthesis 5.

in FIG. 6, from a top view, frame 17 is D-Shaped. In this aspect of theinvention, leaflet 37 c can have a larger area than leaflet 37 a andcorresponding angle 67 c can be greater than angle 67 a. As a result,coaptation edge 57 b can have a greater length than coaptation edge 57a. Alternatively, leaflet 37 a can be larger than leaflets 37 c andcorresponding angle 67 a can be larger than angle 67 c. In a preferredembodiment, angle 67 c is approximately 170 degrees. In alternateaspects of the invention, the sizes of leaflets 37 a-c and the angles 67a-d can be modified in order to optimize the function of valveprosthesis 7.

FIG. 7 shows an alternate valve prosthesis 101 having four leaflets 131a-d and four commissure points 141 a-d. Leaflets 131 a and 131 c areapproximately the same size having approximately the same area. In analternate aspect of the invention, leaflets 131 a and 131 c can bedifferent sizes. Leaflet 131 a is attached to leaflet 131 b atcommissure point 141 a and to leaflet 131 d at commissure point 141 d.Leaflet 131 c is attached to leaflet 131 b at commissure point 141 b andto leaflet 131 d at commissure point 141 c. Free edges of leaflets 131 aand 131 b come together to form coaptation edge 151 a. Free edges ofleaflets 131 b and 131 c come together to form coaptation edge 151 b.Free edges of leaflets 131 c and 131 d come together to form coaptationedge 151 c. Free edges of leaflets 131 d and 131 a come together to formcoaptation edge 151 d. Free edges of leaflets 131 a and 131 c cometogether to form coaptation edge 151 e. Coaptation edges 151 a-e therebycreate a competent seal. In a preferred embodiment, the length ofcoaptation edge 151 e is larger than the length of any of coaptationedges 151 a-d.

Leaflets 131 a-d are assembled to a skirt (not shown), similar to valveprosthesis 1. Commissure points 141 a-d are attached to frame 111 whichis elliptical from a top view. Commissure points 141 a-d are arranged toform angles 161 a-161 d, where the center of frame 111 is the vertex ofthe angles. Frame 111 can be any other shape known to a person ofordinary skill, including but not limited to circular, or D shaped froma top view, or tapered, conical, or cylindrical from a side view. In oneaspect of the invention, angles 161 a and 161 c are larger than angles161 b and 161 d. In a preferred embodiment, angles 161 a and 161 c areapproximately 170 degrees. In an alternate embodiment, one or more ofangles 161 a-d can be modified to optimize the function of valveprosthesis 101 by positioning one or more commissure points 141 a-d onan alternate portion of frame 111 or by modifying the shape or area ofone or more of leaflets 131 a-d. Modifying one or more of angles 161 a-dcan modify the length of coaptation edges 151 a-e.

In an alternate aspect of the invention shown in FIG. 8, from a topview, frame 113 is D-Shaped. In this aspect of the invention, leaflet133 c has a larger area than leaflet 133 a and corresponding angle 163 cis greater than angle 163 a. Furthermore, leaflet 133 a is larger thanleaflets 133 b and 133 d and corresponding angle 163 a can be largerthan angles 163 b and 163 d. In a preferred embodiment, angle 163 c canbe 170 degrees. In alternate aspects of the invention, the sizes ofleaflets 37 a-c and the angles 67 a-d can be modified to optimize thefunction of valve prosthesis 103. Similar to valve prosthesis 101discussed above with respect to FIG. 7, leaflets 133 a-d come togetherto form coaptation edges 153 a-e. In a preferred embodiment, the lengthof coaptation edge 153 e is greater than the length of any of coaptationedges 153 a-d.

The valve prosthesis can replace the function of a tricuspid or bicuspidheart valve including the mitral valve, the aortic valve, the pulmonaryvalve, or the tricuspid valve. The valve can be delivered, for example,transeptally, transapically, transradially, or transatrially.

Implantation of the valve prosthesis will now be described. As discussedabove, the valve prosthesis preferably comprises a self-expanding framethat can be compressed to a contracted delivery configuration onto aninner member of a delivery catheter. The valve prosthesis and innermember can then be loaded into a delivery sheath of conventional design,e.g., having a diameter of less than 20-24 French. Due in part to thefact that the commissure points are longitudinally offset from thecoaptation edges of the leaflets, and due to the ability to maintain alower commissure height, it is expected that the valve prosthesis canachieve a significantly smaller delivery profile than previously-knownpercutaneously-deliverable replacement valves.

The delivery catheter and valve prosthesis are then advanced in aretrograde manner through the femoral artery and into the patient'sdescending aorta. The catheter then is advanced, under fluoroscopicguidance, over the aortic arch, through the ascending aorta and mid-wayacross the defective aortic valve. Once positioning of the catheter isconfirmed, the sheath of the delivery catheter can be withdrawnproximally, thereby permitting the valve prosthesis to self-expand.

As the valve prosthesis expands, it traps the leaflets of the patient'sdefective aortic valve against the valve annulus, retaining the nativevalve in a permanently open state. The outflow section of the valveprosthesis expands against and aligns the prosthesis within theascending aorta, while the inflow section becomes anchored in the aorticannulus of the left ventricle, so that the skirt reduces the risk ofperivalvular leaks.

Alternatively, the valve prosthesis can be delivered through atransapical procedure. In a transapical procedure, a trocar or overtubeis inserted into the left ventricle through an incision created in theapex of a patient's heart. A dilator is used to aid in the insertion ofthe trocar. In this approach, the native valve (e.g. the mitral valve)is approached from the downstream relative to the blood flow. The trocaris retracted sufficiently to release the self-expanding valveprosthesis. The dilator is preferably presented between the valveleaflets. The trocar can be rotated and adjusted as necessary toproperly align the valve prosthesis. The dilator is advanced into theleft atrium to begin disengaging the proximal section of the valveprosthesis from the dilator.

In an alternate aspect of the invention, the valve prosthesis can bedelivered through a transatrial procedure. In this procedure, thedilator and trocar are inserted through an incision made in the wall ofthe left atrium of the heart. The dilator and trocar are advancedthrough the native valve and into the left ventricle of heart. Thedilator is then withdrawn from the trocar. A guide wire is advancedthrough the trocar to the point where the valve prosthesis comes to theend of the trocar. The valve prosthesis is advanced sufficiently torelease the self-expanding frame from the trocar. The trocar can berotated and adjusted as necessary to properly align the valveprosthesis. The trocar is completely withdrawn from the heart such thatthe valve prosthesis self-expands into position and assumes the functionof the native valve.

The foregoing description has been presented for purposes ofillustration and enablement, and is not intended to be exhaustive or tolimit the invention to the precise form disclosed. Other modificationsand variations are possible in light of the above teachings. Theembodiments and examples were chosen and described in order to bestexplain the principles of the invention and its practical applicationand to thereby enable others skilled in the art to best utilize theinvention in various embodiments and various modifications as are suitedto the particular use contemplated. It is intended that the appendedclaims be construed to include other alternative embodiments of theinvention.

What is claimed is:
 1. A valve prosthesis comprising: a valve body; anda self-expanding frame, wherein the valve body includes a first leaflet,a second leaflet, and a third leaflet, wherein the second leafletextends between the first leaflet and the third leaflet such that thefirst and third leaflets are separated from each other by the secondleaflet and wherein the first and second leaflets are sewn together toform a first commissure point and a second commissure point, and thesecond and third leaflets are sewn together to form a third commissurepoint and a fourth commissure point, and wherein the four commissurepoints are sewn to the frame.
 2. The valve prosthesis according to claim1, wherein a first angle is formed between the first commissure pointand the second commissure point with a vertex of the first angle being acenter of the frame, a second angle is formed between the secondcommissure point and the third commissure point with a vertex of thesecond angle being the center of the frame, a third angle is formedbetween the third commissure point and the fourth commissure point witha vertex of the third angle being the center of the frame, and a fourthangle is formed between the fourth commissure point and the firstcommissure point with a vertex of the fourth angle being the center ofthe frame such that the center of the frame is the vertex of each of thefirst, second, third and fourth angles, and wherein the first angle andthe third angle are greater than the second angle and the fourth angle.3. The valve prosthesis according to claim 2, wherein the first angleand the third angle are approximately equal.
 4. The valve prosthesisaccording to claim 2, wherein the first angle and the third angle areapproximately 170 degrees.
 5. The valve prosthesis according to claim 2,wherein the first angle is greater than the third angle.
 6. The valveprosthesis according to claim 2, wherein the second angle and the fourthangle are approximately equal.
 7. The valve prosthesis according toclaim 1, wherein a free edge of the first leaflet and a first free edgeof the second leaflet form a first coaptive edge between the firstcommissure point and the second commissure point, and wherein a secondfree edge of the second leaflet and a free edge of the third leafletform a second coaptive edge between the third commissure point and thefourth commissure point.
 8. The valve prosthesis according to claim 7,wherein the first coaptive edge is approximately equal in length to thesecond coaptive edge.
 9. The valve prosthesis according to claim 7,wherein the second coaptive edge is greater in length than the firstcoaptive edge.
 10. The valve prosthesis according to claim 1, whereinthe second leaflet extends across a center of the frame.
 11. The valveprosthesis according to claim 10, further comprising: a center memberattached to the frame that extends across the second leaflet.
 12. Thevalve prosthesis according to claim 11, wherein the center member isdisposed on an outflow side of the second leaflet and is configured torestrict movement of the second leaflet in the presence of blood flowthrough the valve prosthesis.
 13. The valve prosthesis according toclaim 11, wherein a first end of the center member is attached to theframe between the first commissure point and the fourth commissure pointand a second end of the center member is attached to the frame betweenthe second commissure point and the third commissure point.
 14. A methodof treating a valve disorder in a patient's heart, comprising: loading avalve prosthesis onto a delivery system; advancing the delivery systemand valve prosthesis through an incision into the patient's vasculatureand into the patient's heart; releasing the valve prosthesis from thedelivery system; and withdrawing the delivery system from the patient'sheart, wherein the valve prosthesis includes: a valve body; and aself-expanding frame, wherein the valve body includes a first leaflet, asecond leaflet, and a third leaflet, wherein the second leaflet extendsbetween the first leaflet and the third leaflet such that the first andthird leaflets are separated from each other by the second leaflet andwherein the first and second leaflets are sewn together to form a firstcommissure point and a second commissure point, and the second and thirdleaflets are sewn together to form a third commissure point and a fourthcommissure point, and wherein the four commissure points are sewn to theframe.